Knowledge based valve control method

Abstract

A method associated with a valve controller configured to capture dynamic process conditions for monitoring, diagnosing and maintaining a valve assembly through knowledge-based valve performance criteria. The method includes determining the open and closed positions of a process valve. Measuring the peak torque value required by an actuator to open and close the process valve. Measuring the supply and exhaust pressure required by an actuator to open and close the valve. Determining a deviation zone associated with the peak torque value to open the valve where an alarm is triggered when the torque value falls outside the deviation zone. Creating the dynamic baseline over N th process cycles when the valve is installed in-line.

1. A knowledge based control method associated with a valve package having a process valve, an actuator and a controller, the method comprising:
 obtaining a baseline signature for said valve corresponding to an operating characteristic value of said valve as the valve moves from a first position to a second position in-line as process media is flowing through the valve, the baseline signature comprising a torque profile for the valve; 
 storing said baseline signature in a memory; 
 obtaining an operating signature for said valve corresponding to values associated with said baseline signature each time the valve moves from said first position to said second position in-line as process media is flowing through the valve; 
 comparing said operating signature to the baseline signature; and 
 determining if one or more of the values associated with the operating signature is within an acceptable tolerance deviation from the corresponding one or more values in the baseline signature; 
 wherein said baseline signature is calculated from a rolling average of said operating characteristic determined only after a defined break-in period, the break-in period defined by a period of N cycles, wherein a cycle is defined as movement of the valve from said first position to said second position and from said second position to said first position where N>1. 
 
     
     
       2. The method of  claim 1  wherein said step of obtaining a baseline signature further comprises obtaining said baseline signature as the valve moves from said first position to said second position and back to the first position in-line as process media is flowing through the valve. 
     
     
       3. The method of  claim 1  wherein said step of obtaining an operating signature further comprises obtaining said operating signature each time the valve moves from said first position to said second position and back to the first position in-line as process media is flowing through the valve. 
     
     
       4. The method of  claim 1  further comprising triggering an alarm notification when a peak torque value for the valve falls outside of said acceptable tolerance deviation. 
     
     
       5. The method of  claim 1  wherein said operating characteristic is at least one of the valve's position, torque, supply pressure and exhaust pressure. 
     
     
       6. The method of  claim 1  wherein said first position corresponds to an open position of said valve, and said second position corresponds to a closed position of said valve, and any alarms based on said comparing said operating signature to said baseline signature are prohibited from triggering until after the Nth cycle. 
     
     
       7. The method of  claim 6  wherein said data scan rate is based on the size of said valve, a torque value associated with said actuator and process media flowing through said valve. 
     
     
       8. The method of  claim 1  wherein said baseline signature values are obtained based on a particular data scan rate during a valve cycle wherein a stroke is defined as movement of the valve from said first position to said second position. 
     
     
       9. The method of  claim 1  wherein said first position is a closed position and said second position is an open position, said baseline signature values are obtained based on a first data scan rate when said valve moves from an open to a closed position, and a second data scan rate when said valve moves from a closed position to an open position. 
     
     
       10. The method of  claim 9  wherein said first data scan rate is equal to said second data scan rate. 
     
     
       11. The method of  claim 9  wherein said first data scan rate is not equal to said second data scan rate. 
     
     
       12. The method of  claim 1  wherein the operating signature is stored in a memory. 
     
     
       13. The method of  claim 12  further comprising storing a plurality of said operating signatures taken over a predetermined time interval in said memory. 
     
     
       14. The method of  claim 1  wherein said at least one operating characteristic value of said valve is a peak torque value associated with the amount of torque required to be supplied by said actuator to open the valve from a closed position. 
     
     
       15. The method of  claim 14  where said at least one of an operating characteristic is torque overhead defined as the differential between said peak torque value and said supply pressure. 
     
     
       16. The method of  claim 14  wherein a deviation zone is associated with the peak torque value required to open the valve, said method triggering an alarm when a torque value associated with the operating signature falls outside the deviation zone. 
     
     
       17. A valve system comprising:
 a process valve connected to a pipe line through which process media travels; 
 an actuator mounted on said valve and configured to open and close said valve; and 
 a controller connected to said actuator and configured to supply signals to said actuator to open or close said valve, said controller further configured to obtain a baseline signature for said valve corresponding to at least one operating characteristic value of said valve as the valve moves from said open position to said closed position and from said closed position to said open position in-line as process media travels through said valve, the baseline signature comprising a torque profile for the valve, 
 said controller further comprising a memory device for storing said baseline signature, 
 said controller further configured to obtain an operating signature for said valve corresponding to values associated with said baseline signature each time the valve moves from the open position to the closed position and from the closed position to the open position, said controller comparing said operating signature to said baseline signature; 
 wherein said baseline signature is calculated from a rolling average of said operating characteristic determined only after a defined break-in period, the break-in period defined by a period of N cycles wherein a cycle is defined as movement of the valve from said open position to said closed position and from said closed position to said open position, where N>1. 
 
     
     
       18. The valve system of  claim 17 , wherein any alarms based on said comparing said operating signature to said baseline signature are prohibited from triggering until after the Nth cycle. 
     
     
       19. The valve system of  claim 17 , wherein said baseline signature value is obtained based on a first data scan rate when said valve moves from said open to said closed position, and a second data scan rate when said valve moves from said closed position to said open position. 
     
     
       20. The valve system of  claim 17 , wherein said first data scan rate and said second data scan rate are determined from a look-up table based on a time it takes for the valve to complete a stroke during calibration.